There are a number of different storage systems available for palletized loads; the particular system being dictated by the specific needs of the facility. For example, when small quantity distribution from a storage area is desired a conventional pickout rack system can be employed. This type of system generally includes multi-level storage bays which are either of the single-deep or double-deep type. These bays generally are positioned side-by-side along an aisle to permit easy access to the palletized loads in them. This type of storage facility employs a significant amount of aisle space to permit ready access to the palletized loads with the use of either a single reach or a double reach fork lift truck, depending upon whether the bays are of the single-deep or double-deep type.
While pick-out rack systems are ideally suited for facilities requiring small quantity distribution therefrom, they are highly undesirable for the bulk storage of palletized loads wherein high density storage is desired. Stating this another way, in bulk storage facilities it is not necessary or desirable to provide a large number of aisleways to access the palletized loads. The inclusion of a large number of aisleways takes away valuable space for the storage of articles, and this is highly undesirable for bulk storage facilities wherein only large volume distribution of palletized loads is required.
Drive-in or drive-thru storage systems are commonly employed for the high density, bulk storage of palletized loads. Unfortunately these systems are not sufficiently versatile to permit the easy distribution of small quantities of palletized loads therefrom.
Gravity-type storage systems also are designed for the bulk storage of palletized loads. These systems, like the drive-in and drive-thru systems, lack the desired versatility to permit the same easy distribution of small quantities of palletized loads that can be achieved with pick-out rack systems.
A typical gravity-type system is sold under the trademark Load Bank by Conveyor Logic Inc. of Dutton, Mich. This system employs a pneumatically actuated bag, or tube, for raising rollers in a "pulsing" manner to control the movement of the various pallets down inclined pallet-supporting rails located in vertically aligned storage sections. In addition to lacking the desired versatility for small-quantity distribution of the palletized loads, these gravity-type systems are quite expensive. In fact, they cost approximately five or six times more per pallet setting than drive-thru type systems.
One of applicant's present bulk storage facilities for palletized loads includes an elongate main aisle and a plurality of multi-level pallet storage bays located side-by-side along each elongate side of the main aisle. Ground level sections of the storage bays can be used as staging areas, if desired, and for this purpose are sufficiently wide to permit pallet trucks to be moved into them from the main aisle. However, the various floor section separating the different levels in each of the storage bays are firmly welded in place, and therefore do not provide for the easy modification of different sections of the facility from their high density bulk storage capability to a lower density storage capability of the pick-out type systems.
Another of applicant's storage facilities is a modified drive-in system designed only for the high density, bulk storage of palletized loads. In this facility a plurality of two-level storage bays are located side-by-side adjacent a main aisle along which a pallet-carrying vehicle is adapted to be moved. A plurality of floor sections are utilized in each storage bay to support palletized loads on the second level of each of said bays. The floor sections forming the second level of each bay are movable relative to each other in a horizontal plane to create a space between them into which a pallet-carrying member of a vehicle can be extended for depositing a palletized load on a floor section of the second level adjacent the space.
In operation the pallet-carrying vehicle can be driven into a ground level storage area of a bay with the pallet-carrying member thereof in a retracted position. When this carrying member is aligned with an opening between adjacent spaced-apart floor sections of the second level it can be extended to move the palletized load into the second level and deposit the load on a floor section adjacent the opening. Thereafter, the pallet-carrying member of the vehicle can be retracted and a floor section of the second level adjacent the opening moved to close that opening and, at the same time, create a new opening in the second level in a different area. Thereafter, the pallet-carrying member of the vehicle, with a new palletized load carried thereby, can be extended through the newly created opening to deposit the new load on a different floor section of the second level. The procedure can be repeated to completely load the second level.
In order to completely load the ground level and second level of each bay palletized loads are first loaded on both levels at the rearmost region of the bay. Thereafter the pallets are progressively loaded on both levels in a direction approaching the main aisle.
In the facility described in the preceding paragraph the floor sections forming the second level of the various storage bays are not removed to create any sub-aisle. Moreover, even if sub-aisles were created the palletized loads would still only be removable from the openings at the front of the bays facing the main aisle because the lateral spacing between vertical support members forming the sides of the bays are too close to each other to permit removal of palletized loads from between them.
In summary, the prior art pallet storage facilities lack versatility, and in some cases are excessively expensive. They either are designed for their pick-out capability to permit small quantity distribution therefrom, in which case the required aisle space makes the facility undesirable for the bulk storage of palletized loads. Alternatively, in facilities designed for their bulk-storage capability the number of aisles is kept to a minimum, thereby making them unsuitable for use when small quantity distribution is desired.
From the above discussion it should be apparent that a need exists for a versatile and economical pallet storage facility which can be modified easily for either high density bulk storage of palletized loads or small quantity distribution of palletized loads depending upon the user's particular needs.